1. Field of the Invention
This invention relates to drums such as bass drums, and particularly relates to drumhead stretching mechanisms for stretching drumheads under tension.
2. Description of the Related Art
Drums such as bass drums and snare drums are made of hollow cylinders covered at ends with stretched skins called drumheads, which are supported and fixed by prescribed mechanisms applying tensions thereto. For example, there are provided two types of mechanisms, i.e., a first mechanism in which a clamp frame and lug nuts are directly interconnected using bolts (as disclosed in Japanese Examined Utility-Model Publication No. Sho 59-1263) and a second mechanism in which bolts and a clamp frame are interconnected via latches. In particular, the second mechanism using latches may be frequently used for bass drums having relatively large diameters.
FIG. 9 shows a conventional example of a drumhead stretching mechanism using latches, wherein reference numeral 1 designates a part of a cylindrical wall of a hollow cylinder (or a drum body), both ends of which are open, 2 designates a drumhead stretched over an opening of the hollow cylinder 1 under tension, and 3 designates a drumhead stretching mechanism.
The drumhead stretching mechanism 3 is constituted by various members, i.e., a ring head frame 4 that holds outer circumferential ends 2a of the drumhead 2 and is equipped with the outer circumference of the hollow cylinder 1, a ring clamp frame (or rim) 5 that is equipped with the outer circumference of the hollow cylinder 1 to press the ring head frame 4, a plurality of lugs 6 that are fixed on the outer circumference of the hollow cylinder 1, lug nuts 8 that are incorporated in the lugs 6 and are pressed upwardly by compression coil springs 7, bolts 9 that are engaged with the lug nuts 8, and latches 10 that interconnect together the bolts 9 and the ring clamp frame 5.
The bolt 9 has a head 9B and an external thread portion 9A, a part of which engages with a stopper 11 that is arranged to prevent the bolt 9 from being dropped from the latch 10 when the bolt 9 is taken off from the lug nut 8 and is directed downwards. That is, the stopper 11 is arranged downwardly apart from the latch 10 by an appropriate distance D in order to allow vertical movement of the bolt 9 in a tension adjustment mode of the drumhead 2.
In the drumhead stretching mechanism 3 having the aforementioned structure, when in a tension adjustment mode of the drumhead 2, the bolt 9 is tightened upon rotation using a tuning key (not shown), the distance between the latch 10 and the lug nut 8 is reduced, so that the clamp frame 5 presses the ring head frame 4 to increase tension applied to the drumhead 2. In contrast, when the bolt 9 is loosened, the pressure of the latch 10 applied to the clamp frame 5 is reduced, so that the pressure of the clamp frame 5 applied to the ring head frame 4 is reduced as well, thus reducing the tension of the drumhead 2.
The aforementioned drumhead stretching mechanism 3 is constituted in such a way that the stopper 11 made of a cylindrical nut is arranged to engage with the external thread portion 9A of the bolt 9; therefore, when the external thread portion 9A is relatively long, a human operator (or a user) should rotate and move the stopper 11 multiple times to be arranged in proximity to the latch 10. That is, the human operator is required to perform a troublesome operation in manipulating the stopper 11, which takes a relatively long time.
In the above, the bolt 9 can be taken off from the lug nut 8, wherein the bolt 9 can be freely moved in a vertical direction within a prescribed range of distance D measured from the lower end of the latch 10. Therefore, when the human operator holds and vertically reverses the bolt 9, the latch 10 may float or rattle within the distance D. When the human operator holds and vertically reverses the latch 10, the bolt 9 may float within the distance D.
In addition, the stopper 11 is merely attached to the bolt 9 and cannot prevent the bolt 9 from rotating by itself.
It is an object of the invention to provide a drum and a drumhead stretching mechanism in which a bolt for adjusting tension applied to a drumhead is arranged between a latch and a lug nut, wherein even when the bolt is taken off from the lug nut, it is possible to reliably prevent the bolt from being dropped from the latch, and it is possible to reliably prevent the bolt from unnecessarily rotating and from floating in an axial direction thereof.
In a drumhead stretching mechanism adapted to a drum in accordance with this invention, a bolt for tightening or loosening a drumhead stretched at ends of a hollow cylinder under tension is inserted into a latch that is hooked on a clamp frame for clamping and holding outer circumferential ends of the drumhead, wherein a hollow space for storing an anti-extraction member is formed inside of the latch, so that the shaft portion (specifically, non-thread portion) of the bolt is engaged with the anti-extraction member. The anti-extraction member substantially has a U-shape or a C-shape in plan view with a cutout opening communicating with an anti-extraction hole, into which the bolt is inserted and engaged in a direction perpendicular to the axial direction of the bolt. Thus, it is possible to reliably prevent the bolt from being extracted, from unnecessarily rotating, and from floating in the axial direction of the bolt even when the bolt is taken out from a lug nut, which normally engages with the tip end portion of the bolt.
In the above, the latch and the anti-extraction member can be integrally interconnected together, wherein the anti-extraction member has an anti-extraction hole having a rectangular shape whose short length is slightly less than the outer diameter of the bolt and whose long length is slightly larger than the outer diameter of the bolt.